The present invention relates to tools for use on an aircraft, and more particularly, to tools for localized testing of pressure seals on an aircraft.
Aircraft typically have pressurized cabins that maintain the pressure inside the cabin at a level higher than the atmospheric pressure outside the aircraft during flight. In order to maintain the integrity of the pressurized cabin, openings made in the cabin during the maintenance, and/or upgrade of the aircraft must be sealed and tested. For example, when it is desired to place a new antenna on the exterior of the aircraft, a hole in the fuselage will be required to allow cables or wires to be attached to the antenna. The hole or opening created to allow the cables to travel from inside the aircraft to the exterior of the aircraft need to be sealed prior to putting the aircraft into service. The pressure seals must be able to withstand the pressure differential between the pressurized cabin and the atmospheric pressure when the aircraft is in flight. Therefore, the integrity of the pressure seals must be tested prior to putting the aircraft into service.
The requirements for sealing the openings in the aircraft and the subsequent testing of the pressure seals is typically regulated by a government agency, such as the Federal Aviation Administration (FAA) and/or the airframe manufacturer. These agencies create standards for testing the integrity of the pressure seals used on the aircraft.
In order to test the new pressure seals, the entire cabin is pressurized to a predetermined pressure as specified by the government regulation and/or airframe manufacturer recommendation and held at that pressure for a predetermined length of time to check the integrity of the seal and ensure the safe operation of the aircraft. The process required to pressurize the cabin is time and labor intensive. Typically, repairs and modifications to aircraft are performed inside a hangar where pressure testing cannot be performed without special safety equipment. When it is time to pressure test the aircraft, the aircraft is usually moved to a remote location where it is safe to pressurize the cabin and test the integrity of the pressure seals. In order to move the aircraft to an appropriate pressure testing location, a cockpit-qualified mechanic or pilot is required to move the aircraft. Additionally, ground support, such as a marshalling group or using a walking group, will also be necessary to ensure that the aircraft does not hit anything on its way from the hangar to the pressure testing location. Furthermore, fire protection safe guards are required to be in place which includes having a dedicated fire safety personnel on site during the testing procedure. Therefore, a large amount of labor is required to prepare the aircraft for pressure testing. Because the pressure testing is accomplished via the cabin pressure controller, the aircraft engines need to be operated along with the auxiliary power unit. The operation of the aircraft engines and the auxiliary power unit results in the use of fuel and electricity which increases the cost of pressure testing.
Therefore, it is desirable to be able to test the integrity of the new pressure seals without the need to pressurize the entire cabin. Additionally, if the integrity of the pressure seals can be tested without pressurizing the entire cabin the need to move the aircraft to an authorized pressure testing area can be eliminated. This will result in a savings in labor, fuel and energy costs associated with the pressurized testing of the entire cabin. Therefore, what is needed is a way to locally pressure test the integrity of the new pressure seals without the need to pressurize the entire cabin.
The present invention is directed to a method and apparatus to locally test the integrity of a pressure seal, in accordance with preferred embodiments of the present invention. In one preferred embodiment, a tool is used to locally test the integrity of the pressure seal. The tool has a body with an exterior surface and an interior cavity. A peripheral edge on the body defines an opening that leads to the interior cavity of the body. The body is configured and adapted to withstand a vacuum in the interior cavity without the body of the tool collapsing or buckling. A sealing member is positioned along the peripheral edge. The sealing member provides a fluid tight seal between the peripheral edge of the body and an aircraft on which the tool is being used. The tool is positioned on the aircraft so that the opening in the body of the tool surrounds the pressure seal that is to be tested. The sealing member allows the interior cavity of the body to communicate with the aircraft and the pressure seal so that when a vacuum is created in the interior cavity of the tool the pressure seal also experiences the vacuum. A predetermined level of vacuum is then created in the interior cavity of the tool. After a predetermined length of time as required by the applicable government regulations the level of vacuum in the interior cavity is observed so that the integrity of the pressure seal can be determined.
In another preferred embodiment, the tool also has a vacuum source attached to the body of the tool. The vacuum in the interior cavity of the tool is then provided by selectively operating the vacuum source so that the vacuum source pulls the vacuum on the interior cavity of the tool. The vacuum is then observed after the predetermined length of time to ensure the integrity of the pressure seal.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.